(1) Field of the Invention
This invention relates to a centrifugal clutch for a portable power driven machine and connected to a power source for transmitting the driving power.
(2) Description of the Prior Art
In a portable power driven machine, such as a chain saw, a grass trimmer, etc., it has hitherto been desired that all parts be light in weight and small in size to obtain an overall compact size and a light weight of the machine. Of all the parts of this type of machine, development of a lightweight and small-size centrifugal clutch for transmitting driving power from an internal combustion engine built in the machine to serve as a power source has been delayed as compared with other parts. This is largely due to the fact that difficulties are experienced, if the centrifugal clutch is light in weight and small in size, in achieving dynamic balance in the centrifugal clutch when it is rotated. Centrifugal clutches of the prior art are generally of a construction in which a plurality of drive members forming a pair are located in face-to-face relation on a rotary shaft of the internal combustion engine, and an intermediate member and a driven member are located in association with the pair of drive members respectively. This construction has made it difficult to achieve dynamic balance in a centrifugal clutch unless it is made heavy in weight and relatively large in size.